Ventilation device

ABSTRACT

A ventilation device includes a temperature regulating coil that is capable of changing the cooling capacity at multiple stages, and that cools a supplied-air flow after having undergone total heat exchange by a total heat exchanger, a target indoor-humidity storage unit that stores therein a target indoor humidity that is a target value of the indoor-air humidity, and a control unit that decides the cooling capacity of the temperature regulating coil, such that the humidity of the supplied-air flow becomes the target indoor humidity, based on measurement values of an outside-air temperature sensor and an outside-air humidity sensor when the target indoor humidity is lower than an actual measurement value of the indoor-air humidity measured by an indoor humidity sensor.

FIELD

The present invention relates to a ventilation device.

BACKGROUND

As described in Patent Literature 1, there has conventionally been an air conditioner that controls a compressor in an outdoor device by correcting the rotational speed of the compressor according to the difference between the detected indoor humidity and the indoor temperature during a dehumidifying operation in the air conditioner, that also controls an outdoor fan by correcting the rotational speed of the outdoor fan based on the difference between the detected room temperature and the set indoor temperature, and that performs a dehumidifying operation by alternately performing the operation of the compressor and the operation of the outdoor fan under the corrective control described above.

Furthermore, as described in Patent Literature 2, there has been a ventilation air conditioning device including a temperature sensor that measures the outdoor-air temperature, a humidity sensor that measures the outdoor-air humidity, an air conditioning coil that heats the air to be supplied, and a control unit that controls the air conditioning coil based on the measurement results of the temperature sensor and the humidity sensor, in such a manner that the absolute humidity of the air to be supplied reaches a predetermined value.

CITATION LIST Patent Literatures

Patent Literature 1: Japanese Patent No. 3720220

Patent Literature 2: International Publication No. 2012/077201

SUMMARY Technical Problem

The technique described in Patent Literature 1 does not take the outdoor temperature and humidity information, or an air conditioning load due to ventilation into account. Therefore, the overall air conditioning operation efficiency is not sufficiently considered. This technique in Patent Literature 1 is not sufficiently adequate for the total control in the air conditioner.

In the technique described in Patent Literature 2, parameters for controlling the air conditioning coil are limited to the outside-air temperature and humidity. There is a case where at the start of operation, the humidity in the room is low, and it is therefore necessary to increase the amount of humidification. In that case, when limitations are imposed on the capacity of the air conditioning coil based on the outside-air temperature and humidity conditions, a considerable amount of time is required to bring the interior of the room into a comfortable humidity state. This impairs the comfort.

The present invention has been achieved to solve the above problems, and an object of the present invention is to provide a ventilation device that performs an air supply with an optimal amount of dehumidification at the time of introducing the outside air by ventilation, and that is capable of performing an operation that is less likely to cause a change in the indoor humidity.

Solution to Problem

In order to solve the above-mentioned problems and achieve the object, according to an aspect of the present application, there is provided a ventilation device including: a casing that includes an air-supply passage and an exhaust passage; an air-supply blower that is provided in the air-supply passage, and that blows outdoor air into the air-supply passage to form a supplied-air flow in a room; an exhaust blower that is provided in the exhaust passage, and that blows indoor air into the exhaust passage to form an exhaust-air flow to be discharged outside a room; a total heat exchanger that is located between the air-supply passage and the exhaust passage, and accommodated in the casing, and that performs total heat exchange between the supplied-air flow and the exhaust-air flow; an outside-air temperature sensor that measures a temperature of the outdoor air; an outside-air humidity sensor that measures a humidity of the outdoor air; an indoor humidity sensor that measures a humidity of the indoor air; a temperature regulating coil that is capable of changing a cooling capacity at multiple stages, and that dehumidifies the supplied-air flow after having undergone total heat exchange by the total heat exchanger; a target indoor-humidity storage unit that stores therein a target indoor humidity that is a target value of a humidity of the indoor air; and a control unit that decides a cooling capacity of the temperature regulating coil, such that a humidity of the supplied-air flow becomes the target indoor humidity, based on measurement values of the outside-air temperature sensor and the outside-air humidity sensor when the target indoor humidity is equal to or higher than an actual measurement value of a humidity of the indoor air measured by the indoor humidity sensor.

Advantageous Effects of Invention

According to the ventilation device of the present invention, an effect is obtained where it is possible to perform an air supply with an optimal amount of dehumidification at the time of introducing the outside air by ventilation, and that is capable of performing an operation that is less likely to cause a change in the indoor humidity.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a top perspective view illustrating a configuration of a ventilation device according to a first embodiment of the present invention.

FIG. 2 is a flowchart illustrating an operation flow of the ventilation device.

FIG. 3 is a flowchart illustrating a flow of initial determination control.

FIG. 4 is a flowchart illustrating an operation flow in steady operation control.

FIG. 5 is a time chart illustrating an example of an operation of the ventilation device according to the first embodiment.

FIG. 6 is a system diagram illustrating a configuration of a ventilation device according to a second embodiment and air conditioners.

FIG. 7 is a diagram illustrating a method for varying a high sensible-heat ratio cooling-combining target indoor relative humidity RHm_ken in the ventilation device according to the second embodiment.

FIG. 8 is a flowchart illustrating an operation flow of the ventilation device according to the second embodiment.

FIG. 9 is a time chart illustrating an example of an operation of the ventilation device according to the second embodiment.

DESCRIPTION OF EMBODIMENTS

Exemplary embodiments of a ventilation device according to the present invention will be described below in detail with reference to the accompanying drawings. The present invention is not limited to the embodiments.

First Embodiment

FIG. 1 is a top perspective view illustrating a configuration of a ventilation device according to a first embodiment of the present invention. A ventilation device 23 includes a body casing 1, an exhaust blower 2, an air-supply blower 3, a total heat exchanger 4, a temperature regulating coil 5, a humidifying element 6, an exhaust outlet 7, an air-supply outlet 8, an air-supply inlet 9, an exhaust inlet 10, an outside-air temperature sensor 11, an outside-air humidity sensor 12, a target indoor-humidity storage unit 13, a control unit 14, a remote controller 15, an air-passage switching damper 16, an indoor temperature sensor 17, and an indoor humidity sensor 18.

In the ventilation device 23, the air-supply outlet 8 and the exhaust inlet 10 are provided on the indoor side. On the outdoor side, the exhaust outlet 7 and the air-supply inlet 9 are provided. The ventilation device 23 has a box structure, and is covered with the body casing 1. In the body casing 1, an air-supply passage that communicates the air-supply inlet 9 on the outdoor side with the air-supply outlet 8 on the indoor side, and an exhaust passage that communicates the exhaust inlet 10 on the indoor side with the exhaust outlet 7 on the outdoor side, are formed.

The air-supply blower 3 is incorporated in the air-supply passage to form a supplied-air flow. The exhaust blower 2 is incorporated in the exhaust passage to form an exhaust-air flow. The total heat exchanger 4 is located between the air-supply passage and the exhaust passage. The total heat exchanger 4 continuously performs total heat exchange between a supplied-air flow and an exhaust-air flow to convert the outdoor air to the air to be supplied, and convert the indoor air to the air to be exhausted. On the windward side of the air-supply outlet 8 within the air-supply passage, the humidifying element 6 is provided. Between the air-supply blower 3 and the humidifying element 6, there is provided the temperature regulating coil 5 that dehumidifies the air to be supplied, and adjusts the amount of humidification. A water supply pipe 19 is connected to the humidifying element 6. During the humidifying operation, a water supply valve 20 is opened to supply water for humidification through the water supply pipe 19 to the humidifying element 6.

A primary-side air passage through which an exhaust-air flow passes, and a secondary-side air passage through which a supplied-air flow passes, cross at a right angle inside the total heat exchanger 4. Owing to this structure, the total heat is exchanged between a supplied-air flow and an exhaust-air flow, and therefore the total heat exchanger 4 can perform heat-exchange ventilation.

On the windward side of the total heat exchanger 4 within the exhaust passage, the air-passage switching damper 16 is provided. The air-passage switching damper 16 switches between an air passage 26 through which the air to be exhausted is delivered to the total heat exchanger 4, and a bypass air passage 27 through which the air to be exhausted is delivered directly to the exhaust blower 2 not through the total heat exchanger 4. When the air-passage switching damper 16 is closed, the exhaust air passes through the total heat exchanger 4, and total heat exchange between the exhaust air and the supplied air is continuously performed. When the air-passage switching damper 16 is opened, the exhaust air passes through the bypass air passage 27 provided beside the total heat exchanger 4, and is then converted to the air to be exhausted, and discharged outdoors by the exhaust blower 2.

When an outside-air temperature Toa is lower than the indoor temperature in the transitional season, the ventilation device 23 operates in such a manner as to open the air-passage switching damper 16 to deliver the indoor air to the bypass air passage 27 in order to perform cooling with the outside air by bypass ventilation. In the summer and winter season such as when an air conditioning load is generated, the ventilation device 23 operates in such a manner as to close the air-passage switching damper 16 to deliver the indoor air to the total heat exchanger 4 in order to perform total heat-exchange ventilation intended for the indoor-air heat recovery.

The control unit 14 controls the ventilation operation. The remote controller 15 receives a switching operation of operating modes and the like. The target indoor-humidity storage unit 13 has a target value of the indoor humidity stored therein.

The outside-air temperature sensor 11 measures the outside-air temperature Toa. The outside-air humidity sensor 12 measures an outside-air humidity RHoa. The outside-air temperature sensor 11 and the outside-air humidity sensor 12 are provided between the air-supply inlet 9 and the total heat exchanger 4. The indoor temperature sensor 17 measures an actual indoor temperature Tra, that is, the temperature in the room. The indoor humidity sensor 18 measures an actual indoor humidity RHra, that is, the humidity in the room. The indoor temperature sensor 17 and the indoor humidity sensor 18 are provided between the exhaust inlet 10 and the total heat exchanger 4.

The control unit 14 determines the heating capacity of the temperature regulating coil 5 based on the temperature information that is a measurement result of the outside-air temperature Toa measured by the outside-air temperature sensor 11, and based on the humidity information that is a measurement result of the outside-air humidity RHoa measured by the outside-air humidity sensor 12. The air having passed through the total heat exchanger 4 is heated by the temperature regulating coil 5. The air, having been heated by the temperature regulating coil 5, passes through the humidifying element 6, and is humidified, and then supplied from the air-supply outlet 8 to the interior of the room. At this time, the amount of humidification and the discharge-air temperature are adjusted by the dehumidification amount in the temperature regulating coil 5.

FIG. 2 is a flowchart illustrating an operation flow of the ventilation device. After the start of operation, the control unit 14 executes initial determination control for determining the initial operation state (Step S1). Thereafter, the control unit 14 shifts to steady operation control (Step S2). When there is no operation to finish the device operation (NO at Step S3), the control unit 14 continues the steady operation control. When there is an operation to finish the device operation (YES at Step S3), the control unit 14 finishes the operation of the ventilation device 23.

FIG. 3 is a flowchart illustrating a flow of initial determination control. Initially, the control unit 14 reads an actual measured indoor relative humidity RHra, and a target indoor relative humidity RHm (Step S11). Next, the control unit 14 compares the actual measured indoor relative humidity RHra with the target indoor relative humidity RHm (Step S12). When the actual measured indoor relative humidity RHra is higher than the target indoor relative humidity RHm (YES at Step S12), the control unit 14 operates the ventilation device 23 in a dehumidifying mode A (Step S13). In the dehumidifying mode A, in order to ensure the comfort, the control unit 14 controls the temperature regulating coil 5 such that the dehumidification capacity becomes 100%.

When the actual measured indoor relative humidity RHra is lower than the target indoor relative humidity RHm (NO at Step S12), the control unit 14 determines the humidity state in the room (Step S14). The determination of the humidity state is performed based on whether the actual measured indoor relative humidity RHra is equal to or higher than a thermo-off humidity RHoff. When the actual measured indoor relative humidity RHra is equal to or higher than the thermo-off humidity RHoff, the control unit 14 determines that it is necessary to continue the dehumidifying operation. In order to prevent chattering, it is appropriate to set the thermo-off humidity RHoff to a value that is approximately 5% lower than the target indoor relative humidity RHm.

When the air in the room is in a state where it needs to be dehumidified (YES at Step S14), the control unit 14 operates the ventilation device 23 in a dehumidifying mode B (Step S15). In the dehumidifying mode B, in order to maintain a constant indoor humidity, the control unit 14 automatically determines the capacity of the temperature regulating coil 5, at which the humidity of the air supplied from the ventilation device 23 becomes the target indoor relative humidity RHm, based on the outside-air temperature Toa and the outside-air humidity RHoa. Reference data, in which a combination of the outside-air temperature Toa and the outside-air humidity RHoa is brought into correspondence with the capacity value of the temperature regulating coil 5, that is a so-called map, is held in the control unit 14. Based on the map, the control unit 14 decides the capacity value of the temperature regulating coil 5.

When the air in the room is not in a state where it needs to be dehumidified, that is, when the actual measured indoor relative humidity RHra is lower than the thermo-off humidity RHoff (NO at Step S14), the control unit 14 operates the ventilation device 23 in a dehumidifying mode C (Step S16). In the dehumidifying mode C, it is not necessary to promote dehumidification by using the temperature regulating coil 5. In order to suppress the decrease in discharge-air temperature, and condensation on the discharge grille, which are caused by overcooling and dehumidification, the control unit 14 sets the operation capacity of the temperature regulating coil 5 to 0%, that is, the ventilation device 23 continues the dehumidifying operation in a thermo-off state.

In the dehumidifying mode C, the control unit 14 permits only a heat-exchange ventilation operation, and prohibits a bypass ventilation operation in which heat exchange is not performed. Therefore, the ventilation device 23 can suppress an abrupt decrease in humidity due to ventilation during the steady operation, maintain a high-humidity state at a constant value for a long time, and ensure the comfort.

FIG. 4 is a flowchart illustrating the operation flow in steady operation control. First, the control unit 14 confirms which dehumidifying mode the ventilation device 23 is currently in (Step S21). When the current dehumidifying mode is the dehumidifying mode A (the dehumidifying mode A at Step S21), the control unit 14 determines whether the actual measured indoor relative humidity RHra remains higher than the target indoor relative humidity RHm (Step S22). When the actual measured indoor relative humidity RHra is higher than the target indoor relative humidity RHm (YES at Step S22), the control unit 14 causes the ventilation device 23 to continue the operation in the dehumidifying mode A in order to continue to decrease the indoor humidity (Step S23). In contrast, when the actual measured indoor relative humidity RHra is lower than the target indoor relative humidity RHm (NO at Step S22), the control unit 14 causes the ventilation device 23 to shift to the dehumidifying mode B (Step S24). Due to this control, while monitoring the outside-air temperature Toa and the outside-air humidity RHoa, the control unit 14 operates the temperature regulating coil 5 at an optimal coil-capacity value, and causes the ventilation device 23 to continue the dehumidifying operation.

When the current dehumidifying mode is the dehumidifying mode C (the dehumidifying mode C at Step S21), the control unit 14 determines whether the actual measured indoor relative humidity RHra remains lower than the thermo-off humidity RHoff (Step S25). When the actual measured indoor relative humidity RHra remains lower than the thermo-off humidity RHoff (NO at Step S25), the control unit 14 causes the ventilation device 23 to continue the operation in the dehumidifying mode C (Step S26). When the actual measured indoor relative humidity RHra is increased by ventilation, and then becomes equal to or higher than the thermo-off humidity RHoff (YES at Step S25), the control unit 14 causes the ventilation device 23 to shift to the dehumidifying mode B (Step S24).

When the current dehumidifying mode is the humidifying mode B (the dehumidifying mode B at Step S21), the control unit 14 determines whether the actual measured indoor relative humidity RHra is equal to or higher than an unlimited-capacity return humidity RHon (Step S27). When the actual measured indoor relative humidity RHra is equal to or higher than the unlimited-capacity return humidity RHon (YES at Step S27), the control unit 14 causes the ventilation device 23 to shift to the dehumidifying mode A (Step S23). In order to prevent chattering, it is appropriate to set the unlimited-capacity return humidity RHon to a value that is approximately 5% higher than the target indoor relative humidity RHm.

When the actual measured indoor relative humidity RHra is lower than the unlimited-capacity return humidity RHon (NO at Step S27), the control unit 14 determines whether the actual measured indoor relative humidity RHra is equal to or higher than the thermo-off humidity RHoff (Step S28). When the actual measured indoor relative humidity RHra is equal to or higher than the thermo-off humidity RHoff (YES at Step S28), the control unit 14 maintains the operation of the ventilation device 23 in the dehumidifying mode B (Step S24). When the actual measured indoor relative humidity RHra is not equal to or higher than the thermo-off humidity RHoff (NO at Step S28), the control unit 14 causes the ventilation device 23 to shift to the dehumidifying mode C (Step S26).

FIG. 5 is a time chart illustrating an example of the operation of the ventilation device according to the first embodiment. At the time t0, the control unit 14 executes initial determination control. Because the actual measured indoor relative humidity RHra is higher than the target indoor relative humidity RHm, the control unit 14 causes the ventilation device 23 to start the dehumidifying operation in the humidifying mode A.

At the time t1, because the actual measured indoor relative humidity RHra becomes equal to or lower than the target indoor relative humidity RHm, the control unit 14 causes the ventilation device 23 to shift from the dehumidifying mode A to the dehumidifying mode B.

At the time t2, because the actual measured indoor relative humidity RHra becomes equal to or lower than the thermo-off humidity RHoff, the control unit 14 causes the ventilation device 23 to shift from the dehumidifying mode B to the dehumidifying mode C.

At the time t3, because the actual measured indoor relative humidity RHra becomes equal to or higher than the thermo-off humidity RHoff, the control unit 14 causes the ventilation device 23 to shift from the dehumidifying mode C to the dehumidifying mode B.

At the time t4, because the actual measured indoor relative humidity RHra exceeds the unlimited-capacity return humidity RHon, the control unit 14 causes the ventilation device 23 to shift from the dehumidifying mode B to the dehumidifying mode A.

At the time t5, because the actual measured indoor relative humidity RHra becomes equal to or lower than the target indoor relative humidity RHm, the control unit 14 causes the ventilation device 23 to shift from the dehumidifying mode A to the dehumidifying mode B.

In the case where the current dehumidifying mode is the dehumidifying mode B, as the outside-air humidity RHoa to be introduced becomes lower, the indoor humidity may also decrease. Therefore, in the above control, when the actual measured indoor relative humidity RHra decreases to the thermo-off humidity RHoff, the control unit 14 switches the dehumidifying mode of the ventilation device 23 from the dehumidifying mode B to the dehumidifying mode C.

In the case where the current dehumidifying mode is the dehumidifying mode B, when the outside-air humidity RHoa to be introduced becomes lower, the dehumidification capacity cannot keep up with the lower outside-air humidity RHoa, and therefore the actual measured indoor relative humidity RHra may increase. Therefore, in the above control, when the actual measured indoor relative humidity RHra is higher than the unlimited-capacity return humidity RHon, the control unit 14 switches the dehumidifying mode of the ventilation device 23 from the dehumidifying mode B to the dehumidifying mode A. Due to this control, the ventilation device 23 performs an operation with the maximized amount of dehumidification in order to decrease the indoor humidity as quickly as possible.

When the actual measured indoor relative humidity RHra is between the unlimited-capacity return humidity RHon and the thermo-off humidity RHoff, the control unit 14 determines that the indoor humidity falls within the target range, and causes the ventilation device 23 to continue the energy-efficient humidifying operation in the dehumidifying mode B.

In the above control, the target indoor relative humidity RHm and the actual measured indoor relative humidity RHra are measured and determined based on the relative humidity. However, when the temperature at the measurement location is high, this may result in an unintentional decrease in the relative humidity. In this case, it is possible that the control unit 14 calculates an absolute humidity from the actual measured indoor relative temperature Tra and the actual measured indoor relative humidity RHra, and compares the calculated absolute humidity with a target absolute humidity.

As described above, according to the first embodiment, the control unit 14 decides the capacity value of the temperature regulating coil 5 based on the target indoor relative humidity RHm, the actual measured indoor relative humidity RHra, the outside-air temperature Toa, and the outside-air humidity RHoa, and the ventilation device 23 performs dehumidification while appropriately adjusting the dehumidification capacity. Due to this operation, while maintaining a constant humidity in the room, the control unit 14 switches over the dehumidifying mode when the actual measured indoor relative humidity RHra deviates from the target indoor relative humidity RHm, and can make the actual measured indoor relative humidity RHra closer to the target indoor relative humidity RHm as quickly as possible. This can improve the comfort in a shorter time.

Second Embodiment

A ventilation device according to a second embodiment has the same configuration as in the first embodiment. However, when the ventilation device is used in combination with an air conditioner, the target indoor relative humidity RHm for the ventilation device is changed based on the operation of the air conditioner. FIG. 6 is a system diagram illustrating a configuration of the ventilation device according to the second embodiment and air conditioners.

Air conditioners 22 and the ventilation device 23 along with an outdoor device 21 constitute an air conditioning system 50, and are connected to each other by a refrigerant pipe 24 and a communication line 25. The outdoor device 21 includes a pump that delivers a refrigerant to the refrigerant pipe 24. The outdoor device 21 further includes a fin that radiates heat absorbed by the refrigerant during the cooling operation in the air conditioners 22 and the ventilation device 23. Some of the air conditioners 22 include a remote controller 28. An operation such as switching between on and off of the device operation, or switching over the operation mode, is performed through the remote controller 28.

As a target indoor humidity to be used when the air conditioners 22 that constitute the air conditioning system 50 perform a high sensible-heat ratio cooling operation during a dehumidifying operation, a high sensible-heat ratio cooling-combining target indoor relative humidity RHm_ken is set in the control unit 14. The high sensible-heat ratio cooling-combining target indoor relative humidity RHm_ken is set to a value between a normal target indoor relative humidity RHm and the thermo-off humidity RHoff. It is also possible that the high sensible-heat ratio cooling-combining target indoor relative humidity RHm_ken is set to a fixed value, or a value that varies according to the number of air conditioners that work in conjunction with each other. FIG. 7 is a diagram illustrating a method for varying the high sensible-heat ratio cooling-combining target indoor relative humidity RHm_ken in the ventilation device according to the second embodiment. It is also possible that the value of the high sensible-heat ratio cooling-combining target indoor relative humidity RHm_ken is set so as to become smaller each time the number of the air conditioners 22 that work in conjunction with each other increases by 1, or is set so as to become smaller each time the number of the air conditioners 22 that work in conjunction with each other increases by 2 or more.

FIG. 8 is a flowchart illustrating the operation flow of the ventilation device according to the second embodiment. The operation of the ventilation device 23 in initial determination control (Step S1) is as described in the first embodiment. After the initial determination control, the control unit 14 determines whether the air conditioners 22 that constitute the air conditioning system 50 perform a high sensible-heat ratio cooling operation during a dehumidifying operation (Step S31). When the air conditioners 22 perform a high sensible-heat ratio cooling operation (YES at Step S31), the dehumidification capacity of the air conditioners is decreased. Therefore, in order to maintain or increase the dehumidification capacity of the ventilation device 23, the control unit 14 changes the target indoor relative humidity RHm for the ventilation device 23 from the normal value to the high sensible-heat ratio cooling-combining target indoor relative humidity RHm_ken (Step S32). When the air conditioners 22 that constitute the air conditioning system 50 perform a normal cooling operation (NO at Step S31), a decrease in humidity due to cooling and dehumidification can also be expected. Therefore, the control unit 14 sets the normal value of the target indoor relative humidity RHm as a target indoor humidity for the ventilation device 23 (Step S33).

Thereafter, a steady operation control is executed (Step S2). The operation in the steady operation control is as described in the first embodiment. After the steady operation control, when there is no operation to finish the device operation (NO at Step S3), it is returned to Step S31 and it is determined whether the air conditioners 22 that constitute the air conditioning system 50 perform a high sensible-heat ratio cooling operation. When there is an operation to finish the device operation (YES at Step S3), the operation is finished.

As described above, when the air conditioners 22 do not perform the high sensible-heat ratio cooling operation, the normal value of the target indoor relative humidity RHm is set as a target indoor relative humidity, and therefore an energy-efficient dehumidifying operation is performed with the reduced capacity of the temperature regulating coil 5.

FIG. 9 is a time chart illustrating an example of an operation of the ventilation device according to the second embodiment. At the time t10, the control unit 14 executes the initial determination control, and causes the ventilation device 23 to start the operation in the humidifying mode A.

At the time t11, the actual measured indoor relative humidity RHra becomes equal to or lower than the normal target indoor relative humidity RHm, and also becomes equal to or lower than the high sensible-heat ratio cooling-combining target indoor relative humidity RHm_ken. Therefore, the control unit 14 causes the ventilation device 23 to shift to the operation in the dehumidifying mode B.

At the time t12, because the actual measured indoor relative humidity RHra becomes equal to or lower than the thermo-off humidity RHoff, the control unit 14 causes the ventilation device 23 to shift to the operation in the dehumidifying mode C.

At the time t13, because the actual measured indoor relative humidity RHra becomes equal to or higher than the thermo-off humidity RHoff, the control unit 14 causes the ventilation device 23 to shift from the dehumidifying mode C to the dehumidifying mode B.

At the time t14, because the actual measured indoor relative humidity RHra exceeds the unlimited-capacity return humidity RHon, the control unit 14 causes the ventilation device 23 to shift from the dehumidifying mode B to the dehumidifying mode A.

At the time t15, because the actual measured indoor relative humidity RHra becomes equal to or lower than the high sensible-heat ratio cooling-combining target indoor relative humidity RHm_ken, the control unit 14 causes the ventilation device 23 to shift from the dehumidifying mode A to the dehumidifying mode B.

Based on whether the air conditioners 22 perform a high sensible-heat ratio cooling operation, the control unit 14 switches between the normal target indoor relative humidity RHm and the high sensible-heat ratio cooling-combining target indoor relative humidity RHm_ken, and therefore can extend the area of the dehumidifying mode A in which the temperature regulating coil 5 operates at the capacity value of 100%. This makes it possible to suppress the decrease in humidity caused by dehumidification by the air conditioners 22.

As described above, in the case where the ventilation device 23 is used in combination with the air conditioners 22, the target indoor humidity for the ventilation device 23 is changed based on the cooling-operation information and the refrigerant evaporating temperature information. This makes it possible to prevent the air in the room from being insufficiently dehumidified, and from being overcooled, and therefore to improve the comfort in the room.

In the present embodiment, when the target indoor relative humidity RHm is lower than the actual measured indoor relative humidity RHra measured by the indoor humidity sensor 18, the control unit 14 decides the cooling capacity of the temperature regulating coil 5, such that the humidity of the supplied air becomes the target indoor relative humidity RHm, based on the measurement values of the outside-air temperature sensor 11 and the outside-air humidity sensor 12. Therefore, the ventilation device 23 supplies an optimum amount of dehumidification at the time of introducing the outside air by ventilation, and can achieve a cooling and dehumidifying operation that is less likely to cause a change in the indoor humidity.

INDUSTRIAL APPLICABILITY

As described above, the ventilation device according to the present invention is useful in that the ventilation device that humidifies the outside air, and that introduces the humidified air into a room, changes the amount of humidification relative to a target indoor humidity, and maintains a comfortable indoor humidity. Particularly, the ventilation device according to the present invention is suitable when a separate air conditioner is provided in a room to constitute an air conditioning system along with this ventilation device.

REFERENCE SIGNS LIST

-   -   1 body casing, 2 exhaust blower, 3 air-supply blower, 4 total         heat exchanger, 5 temperature regulating coil, 6 humidifying         element, 7 exhaust outlet, 8 air-supply outlet, 9 air-supply         inlet, 10 exhaust inlet, 11 outside-air temperature sensor, 12         outside-air humidity sensor, 13 target indoor-humidity storage         unit, 14 control unit, 15, 28 remote controller, 16 air-passage         switching damper, 17 indoor temperature sensor, 18 indoor         humidity sensor, 19 water supply pipe, 20 water supply valve, 21         outdoor device, 22 air conditioners, 23 ventilation device, 24         refrigerant pipe, 25 communication line, 26 air passage, 27         bypass air passage, 50 air conditioning system. 

1. A ventilation device comprising: a casing that includes an air-supply passage and an exhaust passage; an air-supply blower that is provided in the air-supply passage, and that blows outdoor air into the air-supply passage to form a supplied-air flow in a room; an exhaust blower that is provided in the exhaust passage, and that blows indoor air into the exhaust passage to form an exhaust-air flow to be discharged outside a room; a total heat exchanger that is located between the air-supply passage and the exhaust passage, and accommodated in the casing, and that performs total heat exchange between the supplied-air flow and the exhaust-air flow; an outside-air temperature sensor that measures a temperature of the outdoor air; an outside-air humidity sensor that measures a humidity of the outdoor air; an indoor humidity sensor that measures a humidity of the indoor air; a temperature regulating coil that is capable of changing a cooling capacity at multiple stages, and that dehumidifies the supplied-air flow after having undergone total heat exchange by the total heat exchanger; a target indoor-humidity storage unit that stores therein a target indoor humidity that is a target value of a humidity of the indoor air; and a control unit that decides a cooling capacity of the temperature regulating coil, such that a humidity of the supplied-air flow becomes the target indoor humidity, based on measurement values of the outside-air temperature sensor and the outside-air humidity sensor when the target indoor humidity is equal to or higher than an actual measurement value of a humidity of the indoor air measured by the indoor humidity sensor.
 2. The ventilation device according to claim 1, wherein the control unit stores therein reference data that defines the cooling capacity to each combination of a temperature and a humidity of the outside air, and determines a cooling capacity of the temperature regulating coil based the reference data and outside-air temperature and humidity sensor measurement results.
 3. The ventilation device according to claim 1, wherein when an actual measurement value of a humidity of the indoor air is higher than the target indoor humidity, the control unit sets a capacity value of the temperature regulating coil to 100%.
 4. The ventilation device according to claim 1, wherein when the indoor air is in an excessively-dehumidified state, the control unit causes the temperature regulating coil to stop cooling the supplied-air flow.
 5. The ventilation device according to claim 1, wherein the target indoor-humidity storage unit stores therein the target indoor humidity as an absolute humidity, and the control unit calculates an absolute humidity of the outdoor air based on an actual measurement value of a temperature of the outdoor air measured by the outside-air temperature sensor, and based on an actual measurement value of a humidity of the outdoor air measured by the outside-air humidity sensor, and when the target indoor humidity is lower than the calculated absolute humidity, the control unit determines a heating capacity of the temperature regulating coil, such that a humidity of the supplied-air flow becomes the target indoor humidity, based on measurement values of the outside-air temperature sensor and the outside-air humidity sensor.
 6. The ventilation device according to claim 1, wherein when the ventilation device and air conditioners constitute an air conditioning system, the control unit changes the target indoor humidity based on number of the air conditioners in the air conditioning system, which are performing a cooling operation. 